Magnetic cooling device

ABSTRACT

A magnetic cooling device is provided, including a magnetocaloric module and a magnetic unit movably disposed around the magnetocaloric module. The magnetocaloric module comprises a bed, a first magnetocaloric member, a second magnetocaloric member, and a third magnetocaloric member received in the bed, wherein the first and third magnetocaloric members are respectively close to a cold end and a hot end of the magnetocaloric module. Specifically, the first, second, and third magnetocaloric members are arranged along a central axis of the magnetocaloric module, and the weight of the third magnetocaloric member exceeds that of the first and second magnetocaloric members. A thermal fluid sequentially flows through the first, second, and third magnetocaloric members to transfer heat from the cold end to the hot end of the magnetocaloric module.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This application relates in general to a cooling device and in particular to a magnetic cooling device having a plurality of magnetocaloric members.

2. Description of the Related Art

Compared with traditional refrigerators and air conditioning equipment, the magnetic refrigerator is relatively simpler in structure and causes less noise pollution as it does not need to use Freon and a compressor. Additionally, since the magnetic refrigerator has the advantages of low energy consumption and low maintenance cost, it has been applied in the field of refrigeration and air conditioning.

As shown in FIG. 1, a related art of an active magnetic refrigerator (AMR) at room temperature has been disclosed in Volume 29, Issue 8, December 2006, Pages 1327-1331, the International Journal of Refrigeration, which applies four different magnetocaloric materials Gd_(0.92)Y_(0.08), Gd_(0.84)Dy_(0.16), Gd_(0.87)Dy_(0.13), Gd_(0.89)Dy_(0.11)serially connected with each other. In this configuration, the four magnetocaloric materials are sequentially arranged from a cold side C to a hot side H along a central axis A thereof. It is noted that the four magnetocaloric materials have substantially equal dimensions but different Curie temperatures.

BRIEF SUMMARY OF INVENTION

An object of the application is to provide a magnetic cooling device, including a magnetocaloric module and a magnetic unit movably disposed around the magnetocaloric module. The magnetocaloric module comprises a bed, a first magnetocaloric member, a second magnetocaloric member, and a third magnetocaloric member received in the bed, wherein the first and third magnetocaloric members are respectively close to a cold end and a hot end of the magnetocaloric module. Specifically, the first, second, and third magnetocaloric members are arranged along a central axis of the magnetocaloric module, and the weight of the third magnetocaloric member exceeds that of the first and second magnetocaloric members. A thermal fluid sequentially flows through the first, second, and third magnetocaloric members to transfer heat from the cold end to the hot end of the magnetocaloric module.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is a perspective diagram of conventional active magnetic refrigeration (AMR) device having four different magnetocaloric materials connected with each other;

FIG. 2 is a perspective diagram of a magnetic cooling device according to an embodiment of the invention;

FIG. 3 is a perspective diagram of a magnetic cooling device according to another embodiment of the invention;

FIG. 4 is a perspective diagram of a magnetic cooling device according to another embodiment of the invention; and

FIG. 5 is a perspective diagram of a magnetic cooling device according to another embodiment of the invention.

DETAILED DESCRIPTION OF INVENTION

Referring to FIG. 2, an embodiment of a magnetic cooling device primarily includes a magnetocaloric module 10 and a magnetic unit 14. The magnet unit 14, such as permanent magnet, electromagnet or a superconductor, is disposed around the magnetocaloric module 10 and can be moved back and forth to apply different magnetic fields to the magnetocaloric module 10. As shown in FIG. 2, the magnetocaloric module 10 includes three magnetocaloric members M11, M12, and M13 received in a bed 11, wherein the bed 11 forms two opening 12 and 13 on opposite sides of the bed 11.

In this embodiment, the magnetocaloric members M11-M13 are separated by two insulating members 15. The insulating members 15 may comprise Aerogel, POM, Teflon or porous material, which allows a thermal fluid to pass therethrough. It is noted that the three magnetocaloric members M11-M13 may be the same material, such as a first order magnetocaloric material, second order magnetocaloric material or alloy, but the weights thereof are different. As shown in FIG. 2, the weights of the three magnetocaloric members M11-M13 gradually increase in a flow direction from the opening 12 (cold end) to the opening 13 (hot end). The mass ratio of the third magnetocaloric member M13 relative to the first magnetocaloric member M11 is substantially from 1.1 to 2. In some embodiments, the magnetocaloric members M11-M13 may comprise a porous structure to allow the thermal fluid to pass therethrough, wherein the porosity thereof is from 30% to 50%.

When the magnetic cooling device is working, the magnet unit 14 reciprocally rotates or moves relative to the magnetocaloric module 10, so as to apply different magnetic fields to the magnetocaloric members M11-M13. When the magnetic field is increased by the magnet unit 14, the temperature of the magnetocloric material will rise. In this state, a thermal fluid may flow into the magnetocaloric module 10 via the opening 12 (cold end) and sequentially pass through the three magnetocaloric members M11-M13 along a central axis A of the magnetocaloric module 10. The thermal fluid is then discharged from the magnetocaloric module 10 through the opening 13, such that heat is transferred to the hot end of the magnetocaloric module 10. Additionally, when the magnetic field is decreased by the magnet unit 14, the temperature of the magnetocaloric members M11-M13 decreases. In this state, the thermal fluid may flow into magnetocaloric module 10 from the opening 13 (hot end) to the opening 12 (cold end), such that the thermal fluid is cooled by the magnetocaloric members M11-M13.

Since heat is continuously transferred from the cold end to the hot end, accumulation of heat and relatively high temperature of the thermal fluid may occur close to the opening 13. Thus, the magnetocaloric member M13 may require a higher weight than the magnetocaloric members M11 and M12, so as to enhance heat pumping power near the hot end. In this embodiment, the weight of the magnetocaloric member M13 exceeds that of the magnetocaloric member M12, and the weight of the magnetocaloric member M12 exceeds that of the magnetocaloric member M11, as shown in FIG. 2. Specifically, the insulating members 15 can prevent heat conduction between the magnetocaloric members M11-M13, thus maintaining a temperature gradient between the magnetocaloric members M12 and increasing efficiency of the magnetic cooling device.

Referring to FIG. 3, another embodiment of a magnetic cooling device comprises three magnetocaloric members M21-M23 with different magnetocaloric materials and weights, wherein the magnetocaloric member M22 is between the magnetocaloric members M21 and M23. Similar to the configuration in FIG. 2, the weight of the magnetocaloric member M23 exceeds that of the magnetocaloric member M22, and the weight of the magnetocaloric member M22 exceeds that of the magnetocaloric member M21. The magnet unit 14 is disposed around the magnetocaloric module 10 and can be moved back and forth to apply different magnetic fields to the magnetocaloric module 10. As the magnetocaloric member M23 is larger and heavier than the other magnetocaloric members M21 and M22, heat pumping power near the hot end is enhanced to improve efficiency of the magnetic cooling device.

Referring to FIG. 4, another embodiment of a magnetic cooling device comprise three magnetocaloric members M31-M33 with different magnetocaloric materials and different weights, wherein the magnetocaloric member M32 is between the magnetocaloric members M31 and M33. Considering the different magnetocaloric properties of the three magnetocaloric members M31-M33, they are arranged in a configuration different from FIGS. 2 and 3, wherein the weight of the magnetocaloric member M31 exceeds that of the magnetocaloric member M32, and the weight of the magnetocaloric member M32 exceed that of the magnetocaloric member M33.

Referring to FIG. 5, another embodiment of a magnetic cooling device comprise three magnetocaloric members M41-M43 with different magnetocaloric materials and different weights, wherein the magnetocaloric member M42 is between the magnetocaloric members M41 and M43. Considering the different magnetocaloric properties of the three magnetocaloric members M41-M43, they are arranged in a configuration different from FIGS. 2-4, wherein the weight of the magnetocaloric member M42 exceeds that of the magnetocaloric member M43, and the weight of the magnetocaloric member M43 exceeds that of the magnetocaloric member M41, so as to enhance heat pumping power and improve efficiency of the magnetic cooling device.

The invention provides a magnetic cooling device having a plurality of magnetocaloric members. An embodiment of the magnetocaloric members may have the same magnetocaloric material, wherein the weight of a magnetocaloric member close to the hot end exceeds that of the other magnetocaloric members. Additionally, the magnetocaloric members may also have different materials. Considering the different magnetocaloric properties of the magnetocaloric members, they may be arranged in various configurations as shown in FIGS. 3-5. The invention can improve efficiency of the magnetic cooling device by applying a plurality of magnetocaloric members with different weights. Specifically, several insulating members may be disposed between the magnetocaloric members to prevent heat conduction, thus maintaining a temperature gradient and increasing efficiency of the magnetic cooling device.

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation to encompass all such modifications and similar arrangements. 

What is claimed is:
 1. A magnetic cooling device, comprising: a magnetocaloric module, comprising: a bed, forming a first opening and a second opening respectively at a cold end and a hot end of the magnetocaloric module; a first magnetocaloric member, received in the bed and close to the first opening; a second magnetocaloric member, received in the bed; a third magnetocaloric member, received in the bed and close to the second opening, wherein the first, second, and third magnetocaloric members are arranged along a central axis of the magnetocaloric module, and the weight of the third magnetocaloric member exceeds that of the first and second magnetocaloric members; a magnetic unit, disposed around the magnetocaloric module to provide different magnetic fields to the magnetocaloric module; and a thermal fluid, sequentially flowing through the first opening, the first, second, third magnetocaloric members, and the second opening, to transfer heat from the cold end to the hot end of the magnetocaloric module.
 2. The magnetic cooling device as claimed in claim 1, wherein the second magnetocaloric member is disposed between the first and third magnetocaloric members, and the weight of the second magnetocaloric member exceeds that of the first magnetocaloric member.
 3. The magnetic cooling device as claimed in claim 1, wherein the mass ratio of the third magnetocaloric member relative to the first magnetocaloric member is from 1.1 to
 2. 4. The magnetic cooling device as claimed in claim 1, wherein the first, second, and third magnetocaloric members comprise first order magnetocaloric material, second order magnetocaloric material or alloy.
 5. The magnetic cooling device as claimed in claim 1, wherein the first, second, and third magnetocaloric members have a porosity from 30% to 50%.
 6. The magnetic cooling device as claimed in claim 1, wherein the first, second, and third magnetocaloric members comprise the same material.
 7. The magnetic cooling device as claimed in claim 1, wherein the first, second, and third magnetocaloric members comprise different materials.
 8. The magnetic cooling device as claimed in claim 1, wherein the magnetic cooling device further comprises two insulating members disposed between the first, second, and third magnetocaloric members, wherein the insulating members comprise Aerogel, POM, Teflon or porous material.
 9. The magnetic cooling device as claimed in claim 1, wherein the magnetic unit comprises a permanent magnet, electromagnet or superconductor.
 10. The magnetic cooling device as claimed in claim 1, wherein the magnetic unit is movable or rotatable relative to the magnetocaloric module. 